Telex MCE325 manual Test and Adjustment Procedures, Cleaning, Test Equipment, Power Supply Test

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2The ribbon connector from the front panel board to the main board is attached at both ends with locking connectors. To unlock the connector, pull the outer shell away from the circuit board. Then, pull the ribbon cable out.

Cleaning

Clean the front panel and case with alcohol or a mild solution of detergent and water, and then wipe off detergent residue with a damp rag. Clean the circuit board (if necessary) with a tetraflouroethane product such as Flux-Off® CZ by Chemtronics®. Use eye protection and avoid breathing the vapors with these solvents. Also, avoid getting the solvent in any of the potentiometers.

Test and Adjustment Procedures

Notes

•All AC voltages are RMS unless otherwise specified.

•All input and output levels were measured using an AC voltmeter calibrated for 1 mW = 0.775V at 600 ohms, but with the 600 ohms in the circuit (0 dBu).

•The following procedures involve changing the MCE325 programming. It may be useful to note the current positions of all jumpers and DIP switches so that they can be returned to their proper positions after testing.

•The inside of the top cover contains a location diagram for the programming jumpers and DIP switches. Place it next to the MCE325 during testing for convenient reference.

•Test procedures are written to be performed in the order presented.

Test Equipment

•Variac

•15 MHz Oscilloscope

•AC Voltmeter

•Frequency Counter

•DC Voltmeter

•Balanced Audio Generator

•400 Hz to 30 kHz bandpass filter with +40 dB of gain

Power Supply Test

1Set a variac to 117 VAC, 60 Hz, and connect the MCE325 to the variac. Observe that each LED blinks on in sequence, and then all LED’s are off.

2Measure the voltage across the secondary of T1 (between test points E7 and E8 on the main circuit board).

Vsec = 18 ±1.8 VAC

3Measure the DC voltage across the “+” and “-“ terminals of bridge rectifier CR1. VCR1 = 23 ±2.3 VDC

4-2C S I - 2 0 0 U s e r I n s t r u c t i o n s

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Contents Model MCE325 Proprietary Notice Return Shipping Instructions End-User License Agreement for Telex Software Table of Contents Operation Diagrams Page Description FeaturesGeneral Front Panel Features Connections, Inputs and OutputsRear Panel Features Intercom LinesMounting Configuration PowerProgramming MCE325 Specifications Power and MechanicalMicrophone Preamplifier Headphone AmplifierMCS325 Specifications ConnectorsStandard four-channel, two-wire configuration Standard two-channel, four wire configuration Page 10M C E 3 2 5 U s e r I n s t r u c t i o n s 11 MCE325 button configurations 12M C E 3 2 5 U s e r I n s t r u c t i o n s Installation Internal Programming and AdjustmentsSwitch Number Switch Function Default Setting Jumper Number Jumper Function Default Setting Internal DIP switches, jumpers and level trimmers Front Panel Setup Mode Lock-out DS4 Remote Talk-off DS7Mechanical Installation Headphone Sidetone Trimmer Adjustment R37Speaker Dim Adjustment R157 Program Assignment IFB Option J4, J5, J16-J18Mounting configurations AC Power and Fuse Electrical InstallationIntercom Lines J8, J9, and J10 Auxiliary Connector, J22 Four-Wire Channel a and B InputProgram Inputs, J14 and J15 External Speaker, J27Remote Microphone Switch Key outputs Expanded IFB OptionISO Connection External HeadsetFront Panel Headset Connections Carbon-microphone headset connector LED Indicators GeneralOperating Instructions Momentary/Latching Button actionVolume Adjustment Front Panel Sidetone Nulling Trimmer AdjustmentPanel Mic/Headset Mic Selection Microphone On/OffFront Panel Programming Call Disable Latch DisableChannel ID Four-channel ListenReset Instant Mic6C S I 2 0 0 U s e r I n s t r u c t i o n s Preventive Maintenance Corrective MaintenanceAccess Factory Support InformationTest and Adjustment Procedures CleaningPower Supply Test Test EquipmentInitial Configuration Keying Output TestFour-Channel, Two-Wire Mode Frequency Response and Level Check, Mic to LineSidetone Null Test and Adjustment Two-Channel, Four-Wire ModeTrue Sidetone Adjust Talk Button Test Point PotentiometerProgram a to Left Headphone Program B to Right Headphone IFB TestProgram to Speaker Four-Wire a Input to Left Headphone Four-Wire B input to Right HeadphonePanel Mic to Channel Test Carbon Mic to Channel TestVOX Test Mic Kill Receive TestCall Transmit Test Mic Kill Transmit TestCall Receive Test Remote Mic Switch Test ISO TestProgram Lockout Test Noise ChecksPage 14C S I 2 0 0 U s e r I n s t r u c t i o n s Packaging Assembly Final Assembly, MCE325Front Panel Assembly Heatsink Assembly Back Panel AssemblyMain PC Board Assembly 4C S I 2 0 0 U s e r I n s t r u c t i o n s Reference 9027-6245-01 Drawing, Section CR1 FB1 #73 Shield Bead 8C S I 2 0 0 U s e r I n s t r u c t i o n s Reference 9027-6245-01 Drawing, Section 10C S I 2 0 0 U s e r I n s t r u c t i o n s RP2 Washer Flat PC Board Assembly, Front Panel DS1-DS814C S I 2 0 0 U s e r I n s t r u c t i o n s Diagrams 2C S I 2 0 0 U s e r I n s t r u c t i o n s Date 7/23/01 Title D\TEMP\AS624501D.cal Title D\TEMP\AS626101C.cal Title D\TEMP\AS626201C.cal Date 7/19/01 Title D\TEMP\AS646401G.dwg Title D\TEMP\BD646401A.cal Title D\TEMP\IS671801A.cal Title D\TEMP\OD635501A.cal Title D\TEMP\OD635502A.cal Title D\TEMP\OD635503A.cal Title D\TEMP\OD635504A.cal Title c\home\cms\benedil\view\9000-646401.CAL Telex Mother Board Mother Board MCE325 Title D\TEMP\SD624601A.cal

MCE325 specifications

The Telex MCE325 is a sophisticated communications headset designed primarily for professionals who demand clarity and reliability in their audio equipment. Renowned for its advanced features and high-quality construction, the MCE325 is a popular choice in various fields, including aviation, broadcast, and live event production.

One of the standout features of the Telex MCE325 is its superior noise-cancellation technology. This headset is engineered to effectively reduce ambient noise, allowing users to focus on important audio signals without distractions. The exceptional passive noise isolation works in tandem with the active noise-cancelling capabilities to ensure that you can communicate clearly, even in loud environments.

The MCE325 also incorporates a high-performance microphone that delivers crystal-clear sound transmission. The flexible boom design allows users to position the microphone for optimal voice pickup, making it suitable for both left- and right-handed users. The microphone’s windscreen further minimizes wind noise, providing an extra layer of clarity during outdoor use.

Comfort is a critical aspect of the MCE325. The headset features plush, padded ear cups that provide excellent comfort for extended use. The adjustable headband ensures a secure fit, catering to a wide range of head sizes and shapes. This ergonomic design minimizes fatigue, allowing users to maintain focus during long hours of operation.

Connectivity is another area where the Telex MCE325 excels. It is versatile enough to work with various devices, thanks to its dual 1/4” and XLR connectors. This flexibility makes it compatible with many audio interfaces and communication systems used in professional settings. The headset also includes a detachable cable, allowing for easy replacement if needed.

The construction of the Telex MCE325 reflects a commitment to durability and longevity. Built with high-quality materials, the headset can withstand the rigors of demanding professional environments. This robustness ensures that users can trust the MCE325 in the most challenging situations, whether it’s in a busy studio or a bustling airport.

In summary, the Telex MCE325 is a versatile and reliable headset designed to meet the needs of professionals across various industries. With its cutting-edge noise-cancellation technology, high-quality microphone, comfort-focused design, versatile connectivity options, and durable construction, it stands out as an ideal choice for anyone seeking superior audio performance and reliability. Whether in communications, aviation, or live broadcasting, the MCE325 delivers an exceptional audio experience.
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